Change bech32 prefix for wasmd

[webmaster128]

Too many software in this ecosystem blindly inherits the Cosmos Hub SLIP44 coin index and the cosmos address prefix. To ensure tooling is compatible with different prefixes, let us use a default that is not cosmos.

We want to use the wasmd binary for a bunch of upcoming testsnets and avoid the overhead of creating a new binary every time. We can use the same address prefix for all of them. I propose wasm.